1. Field of the Invention
This invention generally relates to a bicycle wheel rim structure. More specifically, the present invention relates a bicycle wheel rim structure in which openings in an outer bridge portion of a bicycle wheel rim are covered such that a tubeless pneumatic tire can be used.
2. Background Information
There are many different types of bicycle wheels, which are currently available on the market. Most bicycle wheels include a hub, a plurality of spokes and an annular rim. The hub is rotatably mounted to a part of the bicycle frame. The inner end of each spoke is connected to the hub and the spokes extend outward from the hub. The annular rim is connected to the outer ends of the spokes and includes an outer circumferential part that supports a pneumatic tire. Typically, the spokes of the bicycle wheel are thin metal wire spokes. The ends of the hub are each provided with a flange that is used to couple the spokes to the hub. In particular, holes are provided in the hub flanges. The wire spokes are usually provided with a flange that is formed in the shape of a nail head. The inner end is supported in one of the holes in one of the hub flanges. The outer ends of the spokes typically are provided with threads for engaging spoke nipples, which secure the outer ends of the wire spokes to the rim. In particular, the spoke nipples have flanges, which engage an interior surface of the rim. Alternatively, the spokes may be reversed, with the outer end having the nail head and the inner end having the threads for engaging spoke nipples, which secure the inner ends of the wire spokes to the hub. In any case, an outer bridge portion of the rim is typically provided with a plurality of spoke access openings for installing the spokes to the rim. In some cases, the spoke access openings have sharp edges which can puncture a pneumatic tire tube. Thus, a hole stopper is sometimes provided in each of the spoke access openings thr protecting the pneumatic tire tube. Two examples of such hole stoppers for covering the sharp edges of the spoke access openings are disclosed in U.S. Patent Application Publication No. 2004/0262982 A1 and German Utility Patent No. DE 20 2007 010 082 U1.
In recent years, some wheels have been designed to be used with tubeless tires. The hole stoppers of the above mentioned patent publications cannot completely seal off the spoke access openings. Thus, these hole stoppers are not suitable use for a tubeless wheel. Rather, these tubeless wheels utilize a rim tape to seal the spoke access openings in the outer bridge portion, and thus, prevent air leaks through spoke access openings. One example of a tubeless wheel that uses rim tape is disclosed, in U.S. Patent Application Publication No. 2007/0029869 A1.